Conventionally, most of the recycled aggregate manufactured using concrete mass, which is generated as a result of demolition of a concrete structure, as raw material has been reused as roadbed material for paving a road.
However, since demand for roadbed material for paving a road has decreased due to remarkable reduction of the amount of road buildings in recent years, and it is predicted that recycled aggregate will be excessive in the near future, effort for reusing the above-described recycled aggregate as recycled aggregate for concrete has been made.
JIS A 5021 is defined as a standard of recycled aggregate for concrete. According to this standard, recycled aggregate is classified into H, M, and L.
Among these, “recycled aggregate H” is recycled aggregate for concrete which is manufactured by performing advanced processing of crushing, milling, classifying, etc. on the concrete generated as a result of demolition of a concrete structure or the like. The “recycled aggregate H” is high quality aggregate, which can be treated substantially in the same manner as ordinary aggregate and can be used for any part of a building.
However, in reality, a method for collecting high quality recycled aggregate corresponding to the “recycled aggregate H” from concrete debris is not fully established yet.
In view of this reality, the present inventors propose an invention relating to a method for controlling the quality of recycled aggregate for concrete in The following Patent Document 1.
When a mechanical polishing apparatus, in which a partition member forming a plurality of milling chambers is provided at rotating shaft in a drum body and stuffing is stuffed in the milling chambers, is used, this invention is a manufacturing method with the number of rotations of the partition member divided by the amount of raw material input being set as variable R, recycled coarse aggregate being in a range of the variable R between 0.67 and 1.88 and recycled fine aggregate being in a range of the variable R between 1.00 and 4.67 (however, when quality is assessed in view of absolute dry density and water absorption).
The present inventors referred to the knowledge acquired by the above-described invention, further researched a method for manufacturing high quality recycled aggregate, in particular, recycled aggregate H stipulated in JIS A 5021, and has achieved the present invention.